The present invention generally relates to digital television and, more particularly, it relates to the generation of a time-multiplexed display of channels provided from the head-end of a transmission system.
The basics of television are well known and described in numerous publications. For example, Television Electronics: Theory and Service, by Kiver and Kaufman (1983), which is herein incorporated by reference, describes, among other things, the basics of conventional analog television (see Chapters 7-10, pgs. 159-271). Additionally, the Television Engineering Handbook by Benson and Whitaker (1992), which is also herein incorporated by reference, describes digital television as well as High Definition Television (HDTV) (see Chapters 18 and 24, respectively).
Digital television, in view of its many advantages, is making great progress in its attempts to replace conventional analog television. This progress is driven by many groups and associations. One such association of companies driving digital television is known as the xe2x80x9cDigital HDTV Grand Alliancexe2x80x9d including members such as ATandT, Philips, David Sarnoff Research Center, Massachusetts Institute of Technology and others.
An overview of the strides made by this group are presented in an article by Robert Hopkins entitled xe2x80x9cDigital Terrestrial HDTV for North America: The Grand Alliance HDTV Systemxe2x80x9d published in the IEEE Transactions on Consumer Electronics (Summer 1994) (hereinafter xe2x80x9cthe Grand Alliance articlexe2x80x9d). This article is herein incorporated by reference for all of its teachings regarding the background and basics of digital HDTV systems including the use of Program and Transport Packet Streams.
Although the present invention is generally applicable to digital television and not just digital HDTV, the Grand Alliance article provides background material adequate to illustrate conventional systems and the problems associated therewith. In the Grand Alliance article, FIG. 1, also reproduced herein as FIG. 14, shows a high-level functional block diagram of the Grand Alliance HDTV System encoder. As shown, a video source delivers a video signal to the video compressor where video compression is accomplished in accordance with the MPEG-2 Video standard at the Main Profile/High Level. It should be noted that the problems cited in the article may exist with a Main Profile/Main Level system as well.
The video encoder produces variable-length packets of data called Packetized Elementary Stream (PES) packets. Similar processing occurs for the audio input signals. The video and audio PES packets, along with any ancillary data are presented to a multiplexer (also known as a Transport Multiplexer). The output of the multiplexer is a stream of fixed-length 188-byte MPEG-2 Transport Stream packets. The MPEG-2 Transport Stream packets are presented to the modulator such as a VSB modulator where data is encoded for the channel and a modulated carrier is generated.
After transmission, the signal is received and decoded and displayed on whatever channel the user has selected. In the above-described configuration, a serious drawback exists, however, such that when the user decides to change channels (also known as xe2x80x9cchannel surfingxe2x80x9d) a significant delay may occur between the time the user selects a new channel and when the digital HDTV signal for that channel is actually acquired and displayed on the screen. This delay can be as much as 1 to 2 seconds in duration and, for even the most novice channel surfers, quite annoying. This delay occurs due to the relatively complex decoding schemes implemented in a digital television receiver. This necessarily reduces the rate of channel surfing.
Further, the number of channels broadcast and available to users is increasing. Currently, satellite digital broadcast systems provide 150 channels. As a result, it will become physically taxing for a user to surf the entire space of programs.
Systems have been proposed to overcome these problems. For example, many cable systems provide a rolling-text style of on-screen program guide. Many user""s perceive these guides as boring and of low information content.
Another system which has been proposed is described in U.S. Pat. No. 5,532,748, entitled HYBRID ANALOG/DIGITAL TELEVISION TRANSMISSION SYSTEM issued to Saiprasad V. Naimpally and is incorporated herein by reference. This patent describes a system for including an analog video signal along with the digital television signal to produce a hybrid television signal for use during channel change. This system does not address the physical problems associated with constant button pushing to change channels, nor does it allow digital systems to retain the high quality picture during channel surfing which users have become to expect from analog systems.
The invention is directed to a method and apparatus that generates a time-multiplexed channel surfing signal at television head-end sites. The system includes circuitry that receives channel feeds which are analog signals or digitally encoded signals. The channel feeds are segmented and segments from each feed are combined to produce a combined channel feed which is transmitted with the channel feeds.
The invention is also directed to the generation of the channel feed from the head-end of a transmission system.
The invention is further directed to a head-end delivery system where the combined channel feed may be delivered by a variety of delivery methods including digital broadcast, analog broadcast, and/or transmission via the internet. Each delivery means uses a different back-end.
The invention is also directed to optional receiver control codes, placed into the side information of the time-multiplexed digital signal. The optional receiver control codes provide added features such as one-button jump to current surfing channel for receivers equipped to decode these control codes.